Hydraulic bolt tightener means are in common use for applying equal tension to bolts or studs so as to prevent uneven stress concentration. To avoid the use of special devices which must be moved from one bolt or stud to the next to tension each properly prior to tightening, various forms of hydraulic stud tensioning systems have been built into nut assemblies themselves. U.S. Pat. Nos. 3,362,622 and 4,249,718 describe two forms of such bult-in hydraulic stud tensioning means. In each a tensioning nut is screwed onto the end of the stud and a spacing device is disposed between the tensioning nut and the opposite flange or other foundation surface. After the tensioning nut properly stretches the stud a locking nut within the spacing device is tightened into place, often with the assistance of a tommy bar inserted through an access aperture inside of the spacing device. The tensioning nut and the spacing device are entirely separable from the remainder of the nut assembly when they are taken off the end of the stud.
One of the principal purposes of the present invention is to provide retaining means which holds on the assembly all parts removed from the stud. This is particularly important in installations such as nuclear power facilities where for safety purposes no loose parts are permitted which may accidentally be overlooked during disassembly or reassembly.